Available VRAM Questions

[sivart2000 96]

I have a RTX 2080 and would like some input on how my VRAM is being allocated. I know that windows 10 reserves a good-sized chunk for itself but when running P3D, it shows an available VRAM of between 6.1 and 7.1GB of 8GB available. The average available is between 6.5 and 6.7GB. 

So, some examples:
Sitting in the Cargo stand at PANC with Active Sky, AIG Traffic, Aerosoft PANC, and Orbx Southern Alaska I show 7.1GB available in the VC and it drops to 6.5GB external views. The aircraft I'm using doesn't make any difference. Execpt that I run out of VRAM in the exrternal views with the CS 767 (glad I bought it during the $9.99 sale)

At FSdreamteam KORD with all the Orbx and AIG Active Sky, etc I'm showing 6.2GB available VC and external. 

Typically, though I'm seeing my available VRAM in that 6.5 to 6.7 range.

So, I guess my questions are this; shouldn't my available VRAM be pretty consistent based on what Windows 10 is allocating for itself? 

Shouldn't the resources used by different scenarios in P3D only be reflected in my VRAM usage number and not in my available VRAM number?

Is there a P3D setting that can be adjusted to free up some memory on the availability side of things rather than the usage side?

 

How much available VRAM are other peasants with 8GB cards seeing and is it a consistent number or does it fluctuate depending on view or even in the direction the camera is panned?

 

I seem to recall in one of the more recent P3D versions, maybe 5.1, I was excited to see 6.9-7.1GB available consistently but as soon as I updated to higher versions it reverted back to what I am seeing now. I feel I'm missing something.

[Bob Scott 7,720]

I think what you're missing is the effect of VRAM fragmentation--when an allocation is requested, a single contiguous block of addresses is needed to satisfy the request.

Reported available VRAM is total available minus total allocated without consideration of the largest available contiguous block.  So it's possible to have an allocation request refused due to not having a big enough block available, triggering an OOM even though there is enough unallocated VRAM available in total (but spread across a bunch of too-small blocks).

Increasing VRAM availability on a given system will entail limiting fragmentation by reducing usage enough that you're keeping utilization well below the max.  Use of high-res terrain textures comes immediately to mind as a major VRAM load that can be reduced.

[sivart2000 96]

29 minutes ago, Bob Scott said:

I think what you're missing is the effect of VRAM fragmentation--when an allocation is requested, a single contiguous block of addresses is needed to satisfy the request.

Reported available VRAM is total available minus total allocated without consideration of the largest available contiguous block.  So it's possible to have an allocation request refused due to not having a big enough block available, triggering an OOM even though there is enough unallocated VRAM available in total (but spread across a bunch of too-small blocks).

Increasing VRAM availability on a given system will entail limiting fragmentation by reducing usage enough that you're keeping utilization well below the max.  Use of high-res terrain textures comes immediately to mind as a major VRAM load that can be reduced.

Bruh. Thanks so much! Prior to your reply, I turned off the "run apps in background" option on microsoft edge which bought me about .2GB but it was totally the high res textures causing my issues. Again, thanks a ton!

[sivart2000 96]

On 1/15/2022 at 11:51 AM, Bob Scott said:

I think what you're missing is the effect of VRAM fragmentation--when an allocation is requested, a single contiguous block of addresses is needed to satisfy the request.

Reported available VRAM is total available minus total allocated without consideration of the largest available contiguous block.  So it's possible to have an allocation request refused due to not having a big enough block available, triggering an OOM even though there is enough unallocated VRAM available in total (but spread across a bunch of too-small blocks).

Increasing VRAM availability on a given system will entail limiting fragmentation by reducing usage enough that you're keeping utilization well below the max.  Use of high-res terrain textures comes immediately to mind as a major VRAM load that can be reduced.

I may have spoken too soon. While your advice was helpful, I still feel something is amiss. My usage/available vram was looking something like 5.8/6.5. Turning off high res textures did not change my usage, but it did give me something like 5.8/7.1 when initially spawning into a scenario but, it quicky drops to 5.8/6.5 after panning around the cockpit or switching to external view and then I do not see 7.1 available vram again until I close and restart P3D. There was a point at which, and I can't remember what P3D version it was, I saw steady 7.1 available vram. Perhaps it isn't P3D but rather a Windows update that caused the change but I still feel something isn't right here. 

[IanHarrison 522]

I am not a technical guy but for info. I run a GTX1080 card with 8Gb. With previous versions of P3Dv5, I used to get 6.5 available. Now with the latest 5.3 ++version, I consistently get 7.1 as available.

Yesterday, I ran a torture test of flying a PMDG 747 into EHAM v2 with TE Netherlands. I got around 3.6/7.1 during the flight and  6.1 used of 7.1 as I approached and then it dropped to 6.9/7.1 as I landed. However, on taxi it hit 7.1/7.1 and "blew up". When I flew it again without TE Netherlands I landed and parked successfully at 6.2/7.1.

So in my view, you should be steady at 7.1 as I was. This is not altered by anything that I have adjusted. (As far as I am aware).

[TurboKen 221]

On 1/15/2022 at 6:51 AM, sivart2000 said:

I have a RTX 2080 and would like some input on how my VRAM is being allocated. I know that windows 10 reserves a good-sized chunk for itself but when running P3D, it shows an available VRAM of between 6.1 and 7.1GB of 8GB available. The average available is between 6.5 and 6.7GB. 

So, some examples:
Sitting in the Cargo stand at PANC with Active Sky, AIG Traffic, Aerosoft PANC, and Orbx Southern Alaska I show 7.1GB available in the VC and it drops to 6.5GB external views. The aircraft I'm using doesn't make any difference. Execpt that I run out of VRAM in the exrternal views with the CS 767 (glad I bought it during the $9.99 sale)

 

The CS767 is VERY heavy on the GPU much more so then any other aircraft. Even my 3090 gets a work out when using this aircraft. Try the QW787 or the new iFly737, its made to take advantage of P3d V5 and very well optimized.

Edited January 28, 2022 by TurboKen

[sivart2000 96]

20 hours ago, IanHarrison said:

I am not a technical guy but for info. I run a GTX1080 card with 8Gb. With previous versions of P3Dv5, I used to get 6.5 available. Now with the latest 5.3 ++version, I consistently get 7.1 as available.

Yesterday, I ran a torture test of flying a PMDG 747 into EHAM v2 with TE Netherlands. I got around 3.6/7.1 during the flight and  6.1 used of 7.1 as I approached and then it dropped to 6.9/7.1 as I landed. However, on taxi it hit 7.1/7.1 and "blew up". When I flew it again without TE Netherlands I landed and parked successfully at 6.2/7.1.

So in my view, you should be steady at 7.1 as I was. This is not altered by anything that I have adjusted. (As far as I am aware).

 

2 hours ago, TurboKen said:

The CS767 is VERY heavy on the GPU much more so then any other aircraft. Even my 3090 gets a work out when using this aircraft. Try the QW787 or the new iFly737, its made to take advantage of P3d V5 and very well optimized.

Exactly why I think something is not quite right Ian. The available vram should remain constant or close to it at 7.1 GB for a RTX 2080. And I appreciate the input Turbo but my concern is not my vram usage as I manage that well and rarely run out of vram. It's just that I should have 7.1GB available and something seems to be allocating part of that available vram so that p3d thinks I only have 6.5GB or so available.

[sivart2000 96]

Update: running some tests but think I narrowed it down to DSR factor 2.00x in Nvidia Control panel. I run this in resolution in DCS with no issues but in P3D it appears to reserve an extra .6GB of vram bringing my available down from 7.1GB to 6.5GB. Going to run some scenarios at 1.20x DSR. Looks promising at this setting and the DSR does make for a better image, less jaggies.

[IanHarrison 522]

3 hours ago, sivart2000 said:

Update: running some tests but think I narrowed it down to DSR factor 2.00x in Nvidia Control panel. I run this in resolution in DCS with no issues but in P3D it appears to reserve an extra .6GB of vram bringing my available down from 7.1GB to 6.5GB. Going to run some scenarios at 1.20x DSR. Looks promising at this setting and the DSR does make for a better image, less jaggies.

I looked at this and see that it is NOT available in the program setting only in global. I don't use it at all ( in truth I never knew it existed till now).

[sivart2000 96]

9 hours ago, IanHarrison said:

I looked at this and see that it is NOT available in the program setting only in global. I don't use it at all ( in truth I never knew it existed till now).

Correct so if you set it in global, you will get extra resolution options for your monitor in both the NCP and in the P3D options. So, you can have a resolution higher than your monitor's native resolution and the gpu downscales the image, so you essentially end up with a better image...or some junk like that. I know that is probably not the exact technical description of what DSR does. But I do know, it allows you to run a much lower AA setting and has a far better image with less impact than using high and ultra res texture setting in P3D. But evidentially it must reserve more of the vram which makes sense now that I think about it.

So, of my 8GB vram on my GPU, P3D allows me to use 7.1GB so my PC or GPU is allocating .9GB for irself right off the bat. With a DSR of 2.00x I'm asking the GPU to render twice the resolution to then be scaled to my monitor so my vram available to P3D drops to 6.5GB which equates to roughly, but not exactly, twice as much vram not allocated to P3D.

Perhaps after I sell one gently used kidney, I can upgrade to a RTX 3090. Free shipping. Anyone?

[Bob Scott 7,720]

It's entirely expected that DSR will need more VRAM--and at the driver level, so that explains why an application would see less available video memory.

Good discussion!